Overmoulds of this type are already known from the prior art. These overmoulds of the prior art have the drawback in particular that their sealtightness in relation to the foam which is poured into the mould is not good at the interface between the selvages and the upper edges of the walls delimiting the hook protection cavity. It is necessary to use magnets with strong magnetization which are costly. Besides, if the selvages are placed on the cavities of the moulds in such a way that they project beyond the walls in order to be suspended beyond the walls in the mould itself which will serve to form the final moulded object with a view to good anchoring of the overmould in the moulded object, in particular by at least two contact sides, the foam which has been poured then tends to exert—when taking as a whole—an upward force on its suspended sections of the selvages which tends to slightly dislodge the overmould from the upper edges of the walls and to further reduce the sealtightness at the interface between these selvages and the upper edge of the vertical walls.